Angular position of a magnet which is magnetized radially such as a cylinder magnet or a ring magnet, is sought to be detected in many applications, for example in vehicle drive system. FIG. 1 illustrates a prior art cylinder magnet 10 which is magnetized radially along the diameter. A magnetic sensor 11 placed at the right bottom of the center of the magnet 10, and the magnetic sensor 11 is used to detect the angle orientation of the magnetic field component B generated by the cylinder magnet 10. In this sensing configuration, the magnetic field component B from a north pole N to a south pole S of the magnet 10 is in an opposite direction (180 degree rotated) to a magnetizing direction M. Thus by detecting the angle orientation of the magnetic field vector B rightly below the magnet 10, the angular position in relating to the magnetizing direction M of the magnet 10 can also be determined.
In some applications, referring to FIG. 2, a magnet magnetized radially such as a cylinder magnet 10 is fixed to a spindle 20 along z axis which is perpendicular to the plane xy of the magnetic. In such situations, a magnetic sensor cannot be placed at the right bottom of the center of the magnet 10 to sense the magnetizing direction M. In such situation, a magnetic angular sensor 21 may be placed at the xy plane along the radius r of the magnet 10. And the radius magnetic field component Br is reflective of the angular position α towards the magnetizing direction M. The angular position α versus the value of the radius magnetic field component Br has a relationship as shown in FIG. 5A. And in some other applications, for example as shown in FIG. 3, a magnet 10 may be fixed on a board 30 or embedded in a device and also with a rotatable spindle 20, and a magnetic sensor is not able to be placed either at right bottom of the center of the magnet 10, nor at the plane xy of the magnetic. Accordingly a sensing system is required to detect the angular position towards the magnetizing direction M during these situations where the magnetic angular sensor is neither placed at right bottom of the center of the magnet, nor at the plane of the magnet. And thus a more flexible sensing system with magnetic angular sensor placed side-shafted at either zone A1, A2, A3 or A4 that can be adapted to various situations is required.